Method and apparatus for testing welds



Emmi@ Jam 29 3923 F I K NNARD METHOD AND APPARATUS FOR TEST NG WELDS 2 sHEETs- SHEET l F LED APR 2l 1 921 v WITNESSES 43 4.4. 45'

(ll/KM if? METHOD AND APPARATUS FOR Tasr No WELDS.

F LED APR 21 l 92v.

2 sHEeTs'sHEET 2 wlTNEssl-:s: INVENTOR '/i/Mm/ l n F/f M Si@ f ATTORNEY I Patented dan. 2, i923 entran MAAN@ oesters.

ISAAC F. EINNARD, F WIIJKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WIESTING- HOUSE ELECTRIC @a MANUFACTURING- COMPANY, A CRPQRATION 0F PENNSYL` VANIA.

METHOD AND APPARATUS TESTIG ,IVEILDS Application filed April 21, 1921.

To all 'whom t may concern.'

Be it known that I, ISAAC F. KINNARD, a citizen of the United States," and a resident of Wilkinsburg, inthe county of Allegheny sind State of Pennsylvania,"have invented a new and useful Improvement in Methods of and Apparatus for Testing Welds, of which the following is a'speciication 'Ihis invention relates to testing, more particularly to a method of and apparatus for the testing of welded articles.

Welding is coming into extensive use for joining bodies of various shapes, more especially for welding plates together instead of riveting. In making welds, it is imperative that the strength of the welded portion be com arable to that of the rest of the material. l p'to this time, it has been practically impossible to determine, without a destructive test, the relative strength of the weld and the body of the material.'x As is well known, a weld may appear perfect but still be so defective as to render the welded structure unsafe because of hidden detects in the interior of the welded section.

My invention is designed to provide a ready means of testing the quality of welds without resorting to destructive testsit being among the objects of my invention to devise a method of testing and an apparatus for carrying my method into effect which is simple and accurate. A

My invention is based on the observation that, if the welded portion'oit` an article is uniform and, therefore, of thelsame quality as the body of the material, the electrical resistance and the magnetic reluctance thereof are approximately the same as those ofthe body portion and are uniform along the weld. Any differences in resistance or reluctance usually indicate that the. weld is ldefective in some respects. For instance, if the weld contains hard spots or'blow holes or oxidized' portions, the resistance, or reluctance thereof is increased. My invention contemplates a method of and means for determining the resistance or reluctance of theweld compared to that oan equal amount of the original material.

In practisingmy invention, I may utilize either the current conductivity of the welded material or the flux-carrying capacity thereof to determine the quali-ty of a welded portion of the material. In order to accomplish this, I provide a source of electrical energy which `is so positioned as to cause current or magnetic flux to pass between a pair of electrodes -through the portion of the plate. Mounted on the yoke, between the sa1d electrodes, are a plurali-t of contact members equally spaced an preferably placed symmetrical with respect to the electrodes.. 'Ihe contact members are connected 1n asuitable manner to a measuring instrument.

If 'the electrical method of testing is to be used, directcurrent is passed between the electrodes, and the potential drop across the weld and adjacent the weld are measured by the measuring instrument connected to the contact members, two of which are placed on the sides of the weld and a third adjacent thereto.

If the magnetic method of testing is to be utilized, current is passed through coils surrounding the electrodes which are in contact with the plate and which bridge the gap. rIhe contact members have coils wound in proximity thereto, said coils being connected to a suitable measuring instrument. The dierence in drop of magnetic potential across the weld and adjacent thereto is measured by the current induced in the coils, the said current being measured by the measuring instrument in the circuit.

In the accompanying drawings forming a part hereof and illustrating several embodiments of my invention,

Fig. 1 is a diagrammatic view of my apparatus for testing welds in position for use, illustrating the electrical method of testing;

10o V Y 3 and 4,

Fig. 2 is a diagrammatic view of a similar apparatus for testing welds by the magnetic method;

Figs. 3 and 4 are views similar to Fig. 2 illustrating slightly modified forms ot' the invention;

Fig. 5 is an enlarged detail view, some parts being shown in section, ot the electrode and contact member arrangement of Figs.4 2,

F1 6 is a sectional view along the line VI-l/'I of Fig. 5, and

Fig. 7 is a fragmentary View of Fig. 5 showing a slight modification thereof.

Referring to the embodiment shown in Fig. 1, the yoke or frame 1. has legs 2 and 3 adapted to be placed in contact with or secured to plate 4, the weld 5 of which is to be tested. The frame 1 may be secured to a suitable base or support and the plate to be tested passed thereunder. l

Electrodes 6 and 7 are slidably mounted in yoke 1, the lower ends 8 and 9 respectively thereof being somewhat enlarged and in contact with the plate 4.- Springs 10 and 11 on said electrodes serve to yieldingly hold the lower portions 8 and 9 ,in iirm contact with the plate.. Contact members 14, 15 and 16, the lower ends 17 of which are' pointed, are also slidably mounted in the yoke 1 and are yieldably held in contact with the late 4 by sprin s 18. .The contact mem ers are equal y spaced and preferably placed symmetrically with respect to the electrodes 6 and 7. Y

Conductors19, 20y and 21 lead from contact members 14, 15 and 16, respectively.I to the pairs of contacts or poles 22 and 23 of a double-pole double-throw switch 24, as shown. The central'contacts of switch 24 are connected by conductors. 25 and 26 to a galvanometer 2 I' In order to test welds with this arrangement, the yoke1 is placed upon the plate 4,

` with ,contact members 14 and 15 bridging the weld, and a direct current of about 100 amperes is passed between the electrodes 6 and 7 through leads 12 and. 13. The resistance in the weld 5, if the weld is yimproperly made, is considerably higher than the resistance between contact members 15 and 16. In order to measure the relative resistance of the twoV sections ot' the plate, switch 24 is rst caused to contact with poles 22, where-v by the potential drop between members 14 and 15 is measured by the galvanometer 27. The switch 24 is then reversed, closing the circuit across members 15 and 16, the galvanometer 27 indicating the potential drop across the orirrinal material of the plate. From the relative readings, the difference in .resistance of tlie welded portion and the original material may be readily determined and the quality of the weld thus estimated.

The modification of the invention shown `and 47 in position. l

suitable source of direct current, 40,a va- 7.

riable resistor .41 and an placed inthe line.

Contact members 43, 44 and 45 are secured amnieter being f in position in the yoke 30, the said contact members being equally spaced and sy minetrically placed with respect to electrodes 33 and 34. A connecting member 42, usually ot brass, is secured to the upper ends of said. contact membeis and serves to hold coils 46 A coil46 is wound on member 42 between contact members 43 and 44, and in series therewith is a second coil 47 reversely wound and placed between contact members 44 and 45. Leads 49, 50 and 51 connected to the ends of coils 46 and 47 and the junction 58, respectively, are secured lto the poles 52 and 53 of a double-throw double-pole switch 54. as shown. rThe central poles of said switch are connected'by conductors 55 and 56 to a 9 galvanometer 57.

lin order to measure the reluctance of a weld by this apparatus,1 place the same in the position shown and close switch 38 on contacts 37. This causes a current tollow 'through coils 31 and 32, setting up nia fnetic flux in the iron circuit 30, 33,4, 34. t the same time, due to the drop in potential along the plate 4, magneticpotentials are set up in Contact members 43, 44 and 45.

Switch 54 is then placed in contact with poles 52, and switch -38 thrown into contact with poles 39 to reverse the current.' The change in flux in the plate 4 causes changes of flux in the contact members 43, 44 and 45, causing varying currents to How through coils 46 and 47, the amount of which is indicatedby galvanoineter 57. The operation is then repeated with switch 54 in the reversed position.

By this procedure, there is lirst measured the difference in magnetic potential drop across the..weld and adjacent thereto and then the potential drop in the portion adjacent to the weld. From the data obtained, l the relative reluctance of the weld and thel plate and, therefore, the quality of the weld may be readily determined.

In Fig. 3 is shown an apparatus similar to that of Fig. rThe leads 49 and 50 are secured to two tersecured to the stationary coil thereof. A

source of alternating current 61 of low frequency 1s connected in series with the sta- 1 2 but somewhat simplified. 1^.'

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' terminals of voltmeter 63, a condenser 62 being placed inthe circuit.-

'lhe detailed construction of the yoke member disclosed in Figs. 2 to 4 is as follows: Electrodes 33 and 34 have their upper ends 65 threaded and secured in the soit iron yoke 30. Reels66 are placed upon electrodes 33 and 34 and secured therein by nut 67. The lower ends ot the electrodes are preferably rounded in order to make good contact with a. plate, even though` it is somewhat out of shape.

Depending from yoke 30 is a frame 63 of nonmagnetic material, the lower end of which carries a yoke 69. Contact members 43, 44 and 45 madeof soft iron are secured therein, the lower ends 70, 71 and 72 thereof being adapted to contact with the plate to be tested. A small. air gap may be left between the members and the plate to equalize the eect of scale on the flux -in said members. A brass rod 73, carrying reels 74 and 75, secures the upper' ends of the contact members together, the reels 74 and 75 carrying coils 46 and 47, respectively. The rod 73 provides a nonmagnetic or air core for coils 46 and 47. Springs 76 serve to yieldingly hold the contact members in operative positions. To increase the sensitiveness of the instrument, it may be advisable to use high permeability iron cores.

1n order to limit the relative degree of movement of the contact members, l provide pivots 7 7 at the lower ends of the contact members and mount thereon a lever 7 3,

the central portion 79 of which is slotted;

said portion embracing pivot 77 on contact member 44 and allowing vertical motion thereof with respect to said lever 78.'

An insulating member 80 is mounted on 'frame 68 and is adapted to carry terminals 81,82, 83', 84 and 85 to which are connected leads from coils 31, 46, 47 and 32, respectively, as shown. adapted to make electrical connection with the leads 35, 49, 50,51 and 36, respectively.

1f desired, the testing apparatus may be so constructed as to move on rollers 90 (Fig. 7) so that a continuous record of the quality of a weld may be obtained. y

1 have herein described an apparatus for and method of testingwhich is capable of accurately and with but little manipulation measuring the quality of a weld. Although 1 have described several embodiments of my invention, including bothv electric and magnetic ,methods of testing', my invention is rl`he said terminals are.

not limited to the embodiments shown as it is apparent/that various changes in details ofconstruction and manipulation may he made in my invention without departing fromthe prlnciples set forth.

1 claim as my invention:

1. method ot' testing welds which comprises passing electrical energy through a weld to be tested and comparing thecharlacter of the energy passing through the weld to that. passing through the body'of the material.

2. A method of testing welds which comprises passing electrical energy through a 'weld to be tested and comparing the potential drop in the weld to that. in a corresponding section of the body of the material.

3. A method of testing welds which comprises passing current through a weld to be tested and comparing the potential drop in the weld to that in a corresponding section of the body of the material.

4. A method of testing welds which comprises passing magnetic Hux through a weld to be tested and comparing the potential section of the body of the material.

5. Apparatus for testing welds comprising a plurality of electrodes adapted to bridge a weld, a plurality of contact members therebetween, and means for measuring the potential drop vbetween said members.

6. Apparatus for testing welds comprising a plurality .of electrodes adapted to bridge a weld, a plurality of equally spaced contact members therebetween, and means for' measuring the potential drop between said members.

7. Apparatus for testing-welds comprising' a plurality of electrodes adapted to bridge a weld, a plurality ot' equally spaced contact members therebetween, said members being placed symmetrically with respect to said electrodes, and means for measuring the potential drop between said members. f

8. Apparatus for testing welds comprising a frame, a plurality of electrodes adapted to bridge a weld secured to said frame, a plurality of contact members between said electrodes, and means for measuring the potential 4drop between said members..

9. Apparatus for testing welds comprising a plurality of electrodes adapted to bridge a weld, means for supplying current thereto, a plurality of contact members therebetween and means for measuring the potential drop between said members.

10'.- Apparatus for testing welds comprising a plurality of Velectrodes adapted to bridge a weld,l current-carrying coils on said electrodes for supplying` magnetic energy thereto, a plurality of contact members therebetween and means for measuring the potential drop between said members.

drop in the weld to that in a corresponding i 11.|` Apparatus for testing welds compriselectrodes, current-carrying coils on said electrodes tor` supplying magnetic energy thereto, a plurality of contact members therebetween and means for measuring the potential drop between said members.

12.- Apparatus for testing welds comprising a plurality of electrodes adapted to brldge a weld, means for causing said electrodes to contact with material' to be tested, a plurality of contact members between said electrodes and means for measuring the potential drop between said members.

13. Apparatus for testing welds, comprising a plurality of electrodes adapted to bridge -a Weld, a plurality of contact members therebetween, means for measuring the potential drop between said members, and means for causing said electrodes and members to contact with material to be tested.

14. Apparatus for testing' welds comprisy ing a plurality of electrodes adapted to bridge -a Weld, a plurality of contact members therebetween, means for measuring the lpotential drop between said members, and

springs for causing said electrodes and members to make contact with materlal to be tested.

15. Apparatus ior testing welds comprising a plurality of electrodes adapted to bridge a weld, current-carrying coils on said electrodes 'for su plyino magnetic energy thereto, a plura ity ot contact members therebetween, coils on said members, and means for measuring the potential drop between said members. i

16. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining said electrodes, current-carrying coils on said electrodes and a plurality of contact members carried by said yoke.

' 17. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining said electrodes, current-carrying coils on sai d electrodes and a plurality of spring pressed contact members carried by said yoke.

18. Apparatus for testing welds compris'-4 ing a plurality of Electrodes, a yoke joining said electrodes, current-carrying coils on said electrodes, a plurality ,of contact-members,l carried by said yoke and coils between said members.

19. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining said electrodes, current-carrying coils on said electrodes, a plurality of contact'members carried by said yoke, a yoke connecting said members and coils on said second yoke and between said members.

20. Apparatus for Ltestin welds comprising a plurality of electro es, a yoke joining said electrodes, current-carrying coils on said electrodes, a plurality of contact memneaaerc bers carried by said yoke, and means for allowing relative motlon ot' said members.

21. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining` said electrodes,current-carrying coils. on said electrodes, a pluralltyof contact members, a support therefor, a yoke and means for causing relative motion, of said members comprising a yoke loosely connected to said members and springs interposed between said members and said support.

22. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining said electrodes, current-carrying coils on said electrodes, a plurality of contact members, a support therefor, and meansnfor causing relative motion of said members `comprlsing a yoke loosely connected to said members, springs interposed between said members and said support, and means for jmiting the relative movement of said memers.

23. A method of testing welds which comprises passing Varying magnetic flux through a weld to be tested and comparing the potcntial drop in the weld to that in a correspolnding section of the body of the materia. l

24. A method of testing welds which comprises providing a source of alternating current, passing energy therefrom through a weld to be tested and comprising the character of the energy passing through the Weld with that passing through the body of the material.

25. A method of testing welds which comprises providing a source of alternating current, passing energy therefrom-'through a weld tov be tested and comparing the potential drop in the same with that in a corresponding section of the body of the material.

26. A method of testing welds'which comprises passing electrical energy through a weldto be testedand comparing the character of the energy passing through the Weld tothat passing through the body of the material at a plurality ot' points along the welded portion.

27. .A method of testing welds which comprises passing electrical energy through a Weld to be tested and comparing the character of the energy passing through the, Weld to that passing through the body of the material along the welded portion.

28. Apparatus for testing welds comprising a' plurality of electrodes adapted to bridge a weld, a plurality of contact members therebetween, means for measuring the potential drop between said members, and means for moving said electrodes and contact members along the weldedyportion.

29. Apparatus for testing welds comprising a plurality of electrodes adapted to bridge la weld, a plurality of Contact members therebetween, means for measuring the los ' mme@ potential drop between said members, and a plurality of rollers, said electrodes and Contact members being mounted thereon.

30. Apparatus for testing welds comprising a plurality of electrodes, a yoke joining said electrodes, current-carrying coils on said electrodes, a plurality of Contact memlatter coils.

lin testimony whereof, I have hereunto subscribed my name this 11th day of April,

`llSAAC F. KINNARD. 

